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Conference Object Citation - Scopus: 9A Layered Security Architecture for Corporate 802.11 Wireless Networks(Institute of Electrical and Electronics Engineers Inc., 2004) Erten,Y.M.; Tomur,E.In this study we have investigated the security aspects of wireless local area networks and discussed the weaknesses associated with various conventional 802.11 security protocols such as WEP and 802.1x. We propose an architecture to control access to corporate 802.11 wireless networks, based on the privileges and location of users, using the tested wired network components such as VPNs and Firewalls. The presented architecture reduces the security risks in enterprise level deployment of wireless LANs.Conference Object Citation - Scopus: 8Modeling-Error Based Adaptive Fuzzy Sliding Mode Control for Trajectory-Tracking of Nonlinear Systems(2003) Yu,S.; Yu,X.; Efe,M.O.A novel adaptive fuzzy sliding mode control design is developed for trajectory tracking of a class of nonlinear systems in this paper. This control design uses the modelling error to adaptively estimate the deterministic uncertainties as well as the control gain based on the fuzzy systems approach. By this design, the bounds of the uncertainties are not required to be known in advance, and the robust stability of closed loop systems is analysed in the Lyapunov sense. Simulation results are given to demonstrate the improved performance.Conference Object Citation - Scopus: 16Target Tracking Using Artificial Potentials and Sliding Mode Control(2004) Gazi,V.; Ordóñez,R.In this article we develop an algorithm for capturing/intercepting a moving target based on the sliding mode control method. First, we consider a "kinematic" model (in a sense) for the capture/intercept problem and develop a method for that case. Then, we build on the developed method to include general fully actuated vehicle dynamics for the pursuer agent. The algorithm is robust with respect to the system uncertainties and additive disturbances. Finally, we also provide a numerical simulation in order to illustrate the procedure.Article Citation - WoS: 14Citation - Scopus: 15Yielding of Two-Layer Shrink-Fitted Composite Tubes Subject To Radial Pressure(Springer Heidelberg, 2005) Eraslan, AN; Akis, TYielding of two-layer shrink-fitted composite tubes with axially constrained ends subject to either internal or external pressure is investigated in detail. In the framework of small deformations, a state of plane strain and von Mises yield criterion, analytical expressions are obtained for critical values of the pressure leading to plastic flow. It is shown that, depending on material properties and tube dimensions, different modes of plastic deformation may occur. Yielding may commence at the inner tube or at the outer tube or simultaneously in both tubes. The conditions for different nature of plastic flow are determined. Using analytical expressions obtained for critical values of the parameters and properties of real engineering materials, various numerical examples are handled and the variation of elastic limit pressure with interference and interface radius is explained.Conference Object Complexity Engineering, Evolution and Optimality of Structures(Morgan Kaufmann Pub inc, 1999) Kundu, SComplexity Engineering deals with harnessing the power of Cellular Automata (CA) like simple models to solve real life difficult and complex engineering problems, dealing with systems that have very simple components that collectively exhibit complex behaviors. The state transition rules are generally fixed in a CA, but evolution of the rules, is considered here. To evolve the local rules, we use the Genetic Algorithm (GA) model. The example application described here will serve to demonstrate that the GAs can discover CA rules that give rise to emergent computational strategies by self-organization and exhibit globally coordinated tasks for optimization, with simple local interactions only.Article Citation - WoS: 102Citation - Scopus: 113A 1.6-Mm, Metal Tube Ultrasonic Motor(Ieee-inst Electrical Electronics Engineers inc, 2003) Cagatay, S; Koc, B; Uchino, KA miniaturized metal tube ultrasonic motor, the dimensions of which are 1.6 mm in diameter and 6 rum in length, was developed. Two flattened surfaces with 90-degrees were ground on the outer surface of the stator. Two PZT-based piezoelectric ceramics were bonded onto these flat surfaces. The asymmetrical surface of the stator developed the split of the two degenerated orthogonal bending modes, resulting in a wobble motion. The working frequency of the 1.6-mm motor with 6 mm in length was 130 kHz. A torque of 0.5 mNm was reached at a maximum power of 45 mW with a speed of 45 rad/sec. The maximum efficiency was 16%.Article Citation - WoS: 24Citation - Scopus: 27Global Asymptotic Stability of Cellular Neural Networks With Unequal Delays Lmi Approach(Iee-inst Elec Eng, 2004) Singh, VA criterion for the global asymptotic stability and uniqueness of the equilibrium point of cellular neural networks with unequal delays is presented. The criterion is computationally efficient, since it is in the form of linear matrix inequality (LMI).Article Citation - WoS: 18Oscillation of Second-Order Neutral Delay and Mixed-Type Dynamic Equations on Time Scales(Hindawi Publishing Corporation, 2006) Sahiner, Y.We consider the equation (r(t)(y(Delta)(t))(gamma))(Delta) + f (t, x(delta(t))) = 0, t is an element of T, where y(t) = x(t) + p(t) x(t(t)) and. is a quotient of positive odd integers. We present some sufficient conditions for neutral delay and mixed-type dynamic equations to be oscillatory, depending on deviating arguments tau(t) and delta(t), t is an element of T. Copyright (c) 2006 Y. Sahiner.Article Citation - WoS: 26Citation - Scopus: 26Photoelectronic, optical and electrical properties of TlInS2 single crystals(Wiley-v C H verlag Gmbh, 2003) Qasrawi, AF; Gasanly, NMTo specify the donor energy levels in TlInS2 single crystals, the dark electrical resistivity, photoconductivity and Hall measurements were carried out in the temperature range of 100-400 K, 110-350 K and 170-400 K, respectively. The Hall measurements revealed that the crystals exhibit an anomalous behavior of Hall voltage by changing sign (from p-type to n-type conductivity) at 315 K. By means of the temperature dependence of dark electrical resistivity, Hall coefficient and photocurrent measurements the donor energy levels located at 360, 280, 152 and 112 meV were detected. The photocurrent-illumination intensity dependence follows the law I-Ph proportional to F-gamma with gamma being 1.0 (linear), 0.5 (sublinear), 1.0 (linear) and 1.3 (supralinear) at low, moderate, high and very high illumination intensities indicating the monomolecular in the bulk, bimolecular and strong recombination at the surface, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature (T-m) 245 K. T is observed to shift to higher temperature as F increases, and disappears in the region where I-Ph-F dependence is supralinear. The phenomenon is attributed to the exchange in the behavior of the sensitizing and recombination centers. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.Conference Object Citation - Scopus: 2Effect of Discontinuity Orientation and Spacing on the Blasting Performance in Some Open Cast Mines of Tki-Turkey(International Society for Rock Mechanics, 2003) Kaçar,G.; Özgenoglu,A.; Bilgin,H.A.In this study, the influences of rock mass properties on the blasting performance in open cast mines are investigated. To this end, discontinuity spacings and discontinuity orientations are measured and full scale blasts with various designs are observed in open cast mines of Aegean Lignite (ELI) and Bursa Lignite (BLI) Establishments belonging to Turkish Coal Enterprises (TKI). For each blast, blasting cost is calculated, and particle size distribution representing the fragmentation of muckpile is determined by means of Split-Desktop software using image processing. 50%(K50), 80%(K80) passing sizes and topsize values are used in the determination of blasting performance according to rock mass properties. The relationships between orientation angle, which is the acute angle between the strikes of slope face and major discontinuity, and 50%(K50) and 80%(K80) passing sizes and topsize values and also blasting cost are investigated in order to analyse the influences of major discontinuity orientation on fragmentation and blasting cost. Furthermore, the relationships between discontinuity modal spacing (or block size index) and 50%(K50) and 80%(K80) passing sizes and topsize values and also blasting cost are investigated in order to analyse the influences of discontinuity spacing on fragmentation and blasting cost. In this paper, the trends observed in these relationships are discussed and the importance of it in mining is commented. © 2003 10th ISRM Congress. All rights reserved.
